Phytochemicals and Antimicrobial Potential of Dry Ethanol Extracts from Ailanthus altissima – An Invasive Plant Species for the Bulgarian Flora

Dry ethanol extracts of flowers, leaves, and stem bark of Ailanthus altissima were subject to the determination of the chemical components by GC/MS analysis. Fresh plant material was used for obtaining the plant extracts (in vacuo). Forty-seven compounds were identified from different plant parts. The oxygenated aliphatics were the best represented group in the extracts (flower – 55.44%, leaf – 51.57%, bark – 33.19%), followed by oxygenated monoterpenes (bark – 25.42%; leaf – 15.87%), and diterpenes (flower 14.22%). The major constituent in the flower and leaf extracts was (3Z)-hexenyl hexanoate (28.59%, 12.61%, respectively), while in the bark extract - α-terpinyl acetate (15.55%). The distribution by functional groups, in relation to the total oxygen-containing components, pointed out that the esters were predominated in the three extracts analyzed, followed by alcohols and acids. The EtOH extracts of A. altissima were studied for in vitro antimicrobial activity against gram-positive and gram-negative bacterial strains. The study results showed that the leaf and bark extracts of A. altissima inhibited the growth of six of the tested pathogenic strains. The largest zones of inhibition were measured of ethanol leaf extracts against Bacillus subtilis ATCC 6633 (24.00 ± 0.11 mm) and Klebsiella (clinical isolate – 23.00 ± 1.24 mm). To the best of our knowledge, this is the first study that investigates the phytochemical composition and the antimicrobial activity of the extracts obtained from Ailanthus altissima from Bulgaria. Furthermore, our results revealed that the leaf and bark ethanol extracts could be used as natural antimicrobial agents.